1. Field of the Invention
The present invention is related to a method for analyzing tear film thermograph of contactless tear film thermal imager, and more particularly to a method for analyzing team film thermograph using pattern analysis and parametric analysis technique.
2. Description of the Related Art
Human eyes have a tear film formed on a surface of the cornea to constitute a protection film. The tear film from inside out has a mucus layer, an aqueous layer and a lipid layer to combine into a tear in human eyes. The mucus layer, the aqueous layer and the lipid layer are functionally complementary. The lipid layer serves to prevent water from vaporizing, and the mucus layer facilitates to uniformly spreads tear over and closely contacts with the surface of the cornea.
When a healthy eye blinks, the tear film on the surface of the cornea is refreshed by a new tear drained through a canaliculus and the nasal cavity. However, an eye with the dry eye syndrome has worse secretion and refresh function than a normal eye. Usually, the dry eye syndrome can be confirmed by certain intrusive tests, such as Schirmer test or TBUT test (Tear-film Break Up Time). After giving an eye anesthetic drops thrice, the former test places a slender filter paper strip beneath the lower eyelid and observes a wet length of the filter paper strip after few minutes. The latter test gives drops of fluorescent dye in an eye with the dry eye syndrome and uses slit lamp to observe the first tear break up time after the eye is opened. As the foregoing tests intrude eyes with either filter paper or fluorescent dye, the process of the testing is uncomfortable to patients with the dry eye syndrome. On the other hand, disadvantages of low repeatability and high variability also exist in the foregoing tests.
To solve the aforementioned issues, an infrared thermal imager is employed to take thermographs of the front surface of an eyeball for a patient with dry eye syndrome, keep track of precise temperature variation of a specific location of the cornea within a unit time, acquire a K value and a temperature drop difference ΔT of a temperature-dropping curve in accordance with the temperature variation in a time sequence, and provide a judgment to doctors to diagnose the patient based on a curve with the optimized K and ΔT. Such device acquires images of eyeball for the patient in a contactless manner and verifies the syndrome after an analysis, thereby effectively eliminating the anxiety and fear of patient during the test process and simultaneously enhancing the accuracy of the test.
Clinically, the tear-film break up pattern and lasting time duration vary with patients contracting dry eye syndrome. Each tear-film break up pattern represents a different symptom and different severity. However, the analysis of the tear film break up pattern must fully rely on doctors' judgment and the tear film break up patterns basically associate with recognition of similar images. Due to irregular break up forms of tear films, different doctors may end up with different recognition results and diagnosing judgments, thus impacting on accumulation of clinical case studies and diagnosing experience.